I would say that about 50-60% of the total number of classes offered at Berkeley are 4 units. 15-20% are 3 units and maybe 5-10% are 5 units. The 5 unit ones are primarily language classes from what I can tell. I would bet that the large majority of one’s classes will be 4 units each, so an ordinary load is 4 classes a semester, which is 15-16 units.